The Project:

The project has three active$-$low input switches S$1,$ S$2,$ and S$3$ with external pull$-$up resistors connected to PA$1,$ PA$4,$ and PBO, respectively; and four active$-$low LEDs connected to PA$5,$ PA$6,$ PA$7,$ and PB$6,$ respectively; active$-$low active buzzer connected to PB$3.$ The complete circuit for the project is shown in Figure $1.$ Practically this project is used in systems such as in roulette wheel. $($SK$7)$

$1.$ When the power is connected, the patterns $0001,0011,0111,$ and $1111$ should be displayed alternately at $500$ms intervals continuously.

$2.$ If St is pressed and held, all LEDs should toggle at $500$ms intervals continuously, and there are two variables $($variable $1$ and variable $2)$ that must be consistently random and displayed on the left and right of the $4-$digit $7-$segment display accordingly.

$3.$ If S$1$ is released, the random numbers held by those $2$ variables are displayed on the left and right of the $4-$digit $7-$segment display. The content of the two variables should be limited from $1$ to $6.$

$4.$ If the content of variable $1$ is equal to that of variable $2$ and equal to $6,$ the buzzer sounds for $2000$ms and all LEDs should turn ON$.$

$5.$ If the content of variable $1$ and variable $2$ are the same, the buzzer sounds for $1000$ms$,$ and the LED pattern should be $1001.$

$6.$ If variable $1\text{'}$s content differs from variable $2\text{'}$s$,$ the buzzer sounds for $3000$ms$,$ and the LED pattern should be $0110.$

$7.$ The program sequence switches to step $1,$ after completing any of steps $4,5,$ or $6.$